Analytical compensation of axisymmetric equilibrium fluxes picked up by locked mode detectors in tokamaks

2014 ◽  
Vol 85 (4) ◽  
pp. 043502 ◽  
Author(s):  
Y. H. Ding ◽  
N. C. Wang ◽  
B. Rao ◽  
X. S. Jin ◽  
Z. P. Chen ◽  
...  
Keyword(s):  
Axisymmetric Equilibrium

scholarly journals An Update on Binary Formation by Rotational Fission

2001 ◽  
Vol 200 ◽  
pp. 40-44 ◽  
Author(s):  
Joel E. Tohline ◽  
Richard H. Durisen
Keyword(s):  
Numerical Simulations ◽  
Dynamic Processes ◽  
Nonlinear Saturation ◽  
Detailed Understanding ◽  
Structure And Stability ◽  
Stability Analyses ◽  
Mode Amplitude ◽  
Binary Formation ◽  
Dynamic Growth ◽  
Axisymmetric Equilibrium

During the 1980s, numerical simulations showed that dynamic growth of a barlike mode in initially axisymmetric, equilibrium protostars does not lead to prompt binary formation, i.e., fission. Instead, such evolutions usually produce a dynamically stable, spinning barlike configuration. In recent years, this result has been confirmed by numerous groups using a variety of different hydrodynamical tools, and stability analyses have convincingly shown that fission does not occur in such systems because gravitational torques cause nonlinear saturation of the mode amplitude. Other possible routes to fission have been much less well scrutinized because they rely upon a detailed understanding of the structure and stability of initially nonaxisymmetric structures and/or evolutions that are driven by secular, rather than dynamic processes. Efforts are underway to examine these other fission scenarios.

Self-excited oscillations in three-dimensional collapsible tubes: simulating their onset and large-amplitude oscillations

2010 ◽  
Vol 652 ◽  
pp. 405-426 ◽  
Author(s):  
MATTHIAS HEIL ◽  
JONATHAN BOYLE
Keyword(s):  
Large Amplitude ◽  
Critical Reynolds Number ◽  
Equilibrium Configuration ◽  
Three Dimensional ◽  
Collapsible Tubes ◽  
High Frequency Oscillations ◽  
Equilibrium Configurations ◽  
Axisymmetric Equilibrium ◽  
Outflow Boundary ◽  
Good Agreement

We employ numerical simulations to explore the development of flow-induced self-excited oscillations in three-dimensional collapsible tubes which are subject to boundary conditions (flow rate prescribed at the outflow boundary) that encourage the development of high-frequency oscillations via an instability mechanism originally proposed by Jensen & Heil (J. Fluid Mech., vol. 481, 2003, p. 235). The simulations show that self-excited oscillations tend to arise preferentially from steady equilibrium configurations in which the tube is buckled non-axisymmetrically. We follow the growing oscillations into the large-amplitude regime and show that short tubes tend to approach an approximately axisymmetric equilibrium configuration in which the oscillations decay, whereas sufficiently long tubes develop sustained large-amplitude limit-cycle oscillations. The period of the oscillations and the critical Reynolds number beyond which their amplitude grows are found to be in good agreement with theoretical scaling estimates.

Non-axisymmetric equilibrium reconstruction for stellarators, reversed field pinches and tokamaks

2013 ◽  
Vol 53 (8) ◽  
pp. 083016 ◽  
Author(s):  
J.D. Hanson ◽  
D.T. Anderson ◽  
M. Cianciosa ◽  
P. Franz ◽  
J.H. Harris ◽  
...  
Keyword(s):  
Equilibrium Reconstruction ◽  
Reversed Field ◽  
Axisymmetric Equilibrium

scholarly journals Physical explanation for the galaxy distribution on the (λR, ε) and (V/σ, ε) diagrams or for the limit on orbital anisotropy

2020 ◽  
Vol 500 (1) ◽  
pp. L27-L31
Author(s):  
Bitao Wang ◽  
Michele Cappellari ◽  
Yingjie Peng
Keyword(s):  
Early Type ◽  
Equilibrium Solutions ◽  
Physical Explanation ◽  
Anisotropic Models ◽  
Galaxy Distribution ◽  
Upper Limit ◽  
The Galaxy ◽  
Radial Anisotropy ◽  
Axisymmetric Equilibrium ◽  
Variable Anisotropy

ABSTRACT In the (λR, ε) and (V/σ, ε) diagrams for characterizing dynamical states, the fast-rotator galaxies (both early type and spirals) are distributed within a well-defined leaf-shaped envelope. This was explained as due to an upper limit to the orbital anisotropy increasing with galaxy intrinsic flattening. However, a physical explanation for this empirical trend was missing. Here, we construct Jeans Anisotropic Models (JAM), with either cylindrically or spherically aligned velocity ellipsoid (two extreme assumptions), and each with either spatially constant or variable anisotropy. We use JAM to build mock samples of axisymmetric galaxies, assuming on average an oblate shape for the velocity ellipsoid (as required to reproduce the rotation of real galaxies), and limiting the radial anisotropy β to the range allowed by physical solutions. We find that all four mock samples naturally predict the observed galaxy distribution on the (λR, ε) and (V/σ, ε) diagrams, without further assumptions. Given the similarity of the results from quite different models, we conclude that the empirical anisotropy upper limit in real galaxies, and the corresponding observed distributions in the (λR, ε) and (V/σ, ε) diagrams, are due to the lack of physical axisymmetric equilibrium solutions at high β anisotropy when the velocity ellipsoid is close to oblate.

The Distribution of Pressure Behind a Soft Contact Lens

1984 ◽  
Vol 106 (1) ◽  
pp. 62-65 ◽  
Author(s):  
J. T. Jenkins ◽  
M. Shimbo
Keyword(s):  
Numerical Solution ◽  
Contact Lens ◽  
Shape Factor ◽  
Peripheral Region ◽  
Elastic Membrane ◽  
Equilibrium Equations ◽  
Soft Contact ◽  
Pressure Distributions ◽  
Soft Contact Lens ◽  
Axisymmetric Equilibrium

We determine the pressure distribution behind a soft contact lens that is necessary to keep the lens in conformity with an axisymmetric substrate. The substrate consists of two regions: a central portion, the cornea, supposed to be an ellipsoid; and a peripheral region, the sclera, taken to be a sphere. The pressure is obtained as part of a numerical solution of the axisymmetric equilibrium equations for an initially curved, linearly elastic membrane. The relaxed shape of the lens is assumed to be an axisymmetric ellipsoid with a central curvature and a shape factor different from those of the cornea. The variation in the thickness of the lens from its center to edge is approximated by a polynomial. Pressure distributions are obtained for several typical soft contact lens fittings.

scholarly journals Three-Fluid Axisymmetric Equilibrium Model and Application to Spherical Torus Plasmas Sustained by RF Electron Heating

2015 ◽  
Vol 10 (0) ◽  
pp. 1403084-1403084 ◽  
Author(s):  
Akio ISHIDA ◽  
Akira EJIRI ◽  
Yuichi TAKASE ◽  
Naoto TSUJII ◽  
Hiro TOGASHI ◽  
...  
Keyword(s):  
Equilibrium Model ◽  
Spherical Torus ◽  
Electron Heating ◽  
Axisymmetric Equilibrium
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